The Eyes Have It
Sight is supreme for the iguanas and their relatives, a group of about 1,400 species that some experts call the "sight hounds" of the squamate world. Like humans, these animals rely mostly on vision, not smell, to find their dinners and their mates . . . and to figure out what other members of their species are telling them.
Other than the occasional hiss, squamates tend to be silent, but the sight hounds can definitely communicate. For these animals, movement and color change--things they can see, not hear--are a kind of language. Lashing tails or hisses can mean "Back off!" but so can head bobs and push-ups. A change in skin color may mean "I'm asleep" or "I'm looking for a mate." Look closely at these animals: you may be able to read their minds!
This diagram shows the relationships among these living squamate groups. Close relatives are near each other on the diagram and are separated by fewer branches. Distant relatives are farther apart.
The so-called "sight hounds" include iguanas and their relatives, the chameleons and their relatives and agama (uh-GAH-ma) lizards. Photos in the tree indicate members of this group that were represented in this exhibition by live specimens; fossils that were on display are indicated by name.